Tachometer-magnet and mount for the same.



T. J. FISCHER. TACHOMETER MAGNET AND MOUNT FOR THE SAME.

' APPLICATION FILED OCT-1 1914.

1,155,346. Patented 0%. 5,191

COLUMBIA PITANOGRAPH COWWASHXNGTON, n. c.

'row gap or split between them, and de- UNITED ST S PA E T ormon.

T'IHEODORE J. FISCHE or cnroaeo, ILLINOIS, ASSIGNOB To STEWART-WARNERsrEEnoMETER OORPORATION, or oHIoAoo, ILLINOIS, A CORPORATION OFILLINOIS.

Specification of Ijietters Patent.

' rAoHoMRTER-MAGNET AND MOUNT F R THE'SAMQEI Patented oeea, 1915.

Application filed. October 1, 1914. Serial No. 864,523.

To all whom it may concern Be it known that I, THEODORE J (FISCH R, acitizen of the United States, residingat Chicago, in the county of Cookand State of Illinois, have invented new and useful Improvements inTachometer-Magnets and Mounts for the Same, of-which the follow ing isaspecification, reference being had to the accompanying drawings, forminga part thereof. 1

The purposeofthis invention is to provide an improvedconstruction oftachometer magnet and mount for the same adapted to Y carry and havingassociatedwith it, .a calior bot-hf Y It consists in the elements and"features of constructionshown and' describedfas indicated'i nptlieclaims," 7

In the" drawingsfFigure 1 is" a perspective view of a magnetanditsmount. embodying this invention.- Fig; '2 is'a direct top plan viewof'the same. 5 Figs is-an axial section brating or a teinp'e raturecompensating shunt "of the line, 33, on-fl ig. 2. Fig 4: is a section ofthe line, 4.-4E, On Fig. 2. Fig. 5

is a section of the line, 55, on Fig. 3.

V, 'Th6 magnetshown inithe drawings is of the split-ring type, that is,one which is formed in the shape *of' a -;ring with the poles broughtnear'together leaving a narsigned to'be mounted for rotation about itsaxis. One purpose of the constructiton is to make the magnet and allparts directly associated with it in the simplest form possible and soas to occupy minimum space in the casing, in which'it is mounted, as apart of a tachometer; and "for that purpose the mount, which isneecssarily of non-magnetic metal, is constructed so as not to-pro-.trude in any direction beyond the surface of the magnet itself.

' The magnet, l, having'its central aperture, l communicating with thegap or split, 1", between themagnet poles, is completely occupied the'mount,-- 2, which isf'a' 'un'i- 1 tary 'member made of non-magneticmetal,

comprising the circular portion which 0am;-

pies theci-rcularcentral opening of the magnet, and spur or tang, 2*",extending therefrom-occupying the split or gap between the magnet-poles,By this means the mount and magnet are made relatively non-rotatablewithout the necessity of providing "any means for securing the one tothe other, the tang, 2%engag1ng the gap, 1 serving the purpose-ofsecuring them together for rotation. The mount is designed to be made'ofsuch size as to make a drive fit in the centralaperture of the magnet,and it maybe slightly upset, if necessary, still further to insure 1ts'rigidity with the magnet. The

thereinto; this spindle being hollow from the upper end nearlyto thelower end for -mount has a steel orother hard metal stem 5 or spindle,3, rigid'with sa'id mount at the center thereof, being preferably driventight the purpose ofaccommodating the spindle of the drag element, notshown in'the drawings, whoselower end-is stepped in the bear- Ing, 3at'thebottom ofithefcavit'y of said spindles, Onithe under oriback-sideof the fmagnet, thatflls, :the: side;rom' which the spindle, '3,projects, there iszmounted a calibrating' shunt 'plate,.4, which is athin steel member held firmly to the under-side of the mount by'means ofashoulder, 3", on the spindle, betweenwhich and;the shunt, .4,

a washer, 50,*may be interposed, merely for increasing the area'ofbearing upon the shunt when the spindle is. driven tightly into themount.- By this means the shunt, 4, is

held very tightly against the under-side of head, 4, pressed closelyagainst the side of the magnet, lapping usually both its poles, but{always lapping one pole, and in position so'that by a: littlexmovementabout the spindle it may lap the'othe'r pole more or less. It is held sotightly thatno movement can-possibly occur duringtheoperation of theinstrument; but it is possible by using a proper tool .to press against.it at'either tion. Upon I the other- .sideofithe magnet there is pivotedto't'he'mount,2, a t emperature compensating shunt plate, 5. The pivotof thisplate tothe mount-, is preferably at the opposite sideof'thespindlefromthat at which the magnet poles are situated, and the shuntextends. from its pivot, lying closely against the side of the mount, tothe 'the mount andwith its segmental end or s I poles, upon which itlaps laterally, always lapping upon one pole and adapted to lap more orless on the other according to the adjustment of its position which isto be elii'ected by the thermostatic device, which will be described.Since this shunt, pivoted and extending as described, must extend acrossthe axis of the magnet and would, therefore, extend across the spindleof the dragelement when such spindle is mounted as described in thehollow spindle, 3, said temperature compensating shunt has a centralaperture, 5 large enough to encompass the spindle of the drag-elementwhen it is positioned as described within the spindle of the magnet, andto allow for all necessary movement, of the shunt about its pivot whichmay be caused in the operation of the thermostatic temperaturecompensating device.

The mount, 2, has formed in it upon the side upon which the temperaturecompensating shunt, 5, is situated, an annular pocket, 2, which,however, need not be a complete annulus, that is may not extend all theway around, and as shown does not completely encircle the axis. In thispocket there is lodged the thermostatic device, 6, which is abi-metallic bar bent in a form nearly circular so as to be lodged in theannular pocket, 2, one end of this thermostatic device (bimetallic bar)being pinned fast to the mount by means of pin, 7, binding that end ofsaid device in a seat which is provided for it, at one end of theincompletely annular pocket, as in Fig. 2. The free end of thethermostatic bi-metallic bar is adapted for engaging the temperaturecompensating shunt, 5, by having a notch, 6, near the end, leavingstanding at the end a small tooth, 6 which engages a slot, 5, extendingin the said shunt, 5, radially with respect to the pivot of the shunt.

lhe segmental head, 5, of the shunt, 5, is designed to lap at all timesfor a considerable portion of its width on one pole and it has the edgetoward the other pole cut obliquely in respect to the edge of said otherpole so that as the shunt is moved or lapped on said other pole theinitial lap occurs over a triangular area, which increases from theinner angle of the triangle, as the shunt is moved, so that the increaseand decrease of the area of the shunt lapped upon said pole changesgradually, the lap beginning with a very minute area of the corner ofthe triangle, and increasing, not proportionately to the angularmovement of the shunt about its pivot, but, at a rate which depends bothupon that angular movement and the slope of said oblique edge withrespect to the proximate edge of the magnet pole. The form of thissloping edge, not only the angle of its slope but whether it shall be ina straight line or otherwise, is adapted to the thermostatic device,that is, to the amount of movement which that thermostatic device isadapted to give to the shunt for a given change of temperature withinthe range in which compensation is to be made, and thus saidcompensation can be made as accurate as desired.

I claim 1. A tachometer magnet in the form of a split-ring incombination with an integral mount for the same of non-magnetic metaloccupying the central aperture and the gap of the said ring, the mountbeing flush with the lateral surfaces of the magnet at both sides.

2. In a tachometer a magnet in the form of a split ring, in combinationwith an integral mount for the same of non-magnetic metal which occupiesthe central aperture of the magnet; a calibrating shunt plate heldtightly to the mount at one side having a segment which laps both polesto the magnet, and means for holding the shunt with its said segmenttightly in lateral frictional contact with the magnet.

3. A tachometer magnet in the form of a split ring in combination withan integral mount for the same of non-magnetic metal occupying thecentral aperture of the ring, the mount being flush with the lateralsurfaces of the magnet at both sides, and a calibrating shunt plate heldtightly to the mount at one side, having a segment which laps both polesof the magnet, and means for holding the segment tightly in lateralfrictional contact with the mount and magnet.

4:. A tachometer magnet in the form of a split ring in combination withan integral mount for the same of non-magi-ctic metal occupying thecentral aperture of the magnet, said magnet having on one side atemperature compensating shunt, pivoted to the mount on that side, andlapping laterally on one pole of the magnet, and a thermostatic deviceconnected to the mount and to the shunt for swinging the latter aboutits pivot to cause it to approach and depart from, and to lap more orless on the other pole of the magnet.

5. A tachometer magnet in the form of a split ring in combination withan integral mount for the same of non-magnetic metal occupying thecentral aperture of the magnet, the mount being flush with the lateralsurfaces of the magnet at both sides; a tem-.

perature compensating shunt pivoted to the mount at one side of themagnet and lapping laterally on one pole thereof, and adapted to bemoved about its pivot to lap upon the other pole, the mount having anannular pocket in the side at which the shunt is piv oted; athermostatic element lodged into the annular pocket and secured at oneend of the mount and connected at the other end with the shunt formoving the latter about its pivot by changes of temperature of saidthermostatic element.

6. A tachometer magnet in the form of a" split ring in combination Witha mount for the same, occupying the central aperture of.

the ring; a temperature compensating shunt pivoted to the mountat oneside of the magnet and lapping laterally on one pole therethe mountandhaving the other end engaging said shunt for moving the latter aboutits pivot, t'he-edge of the shunt which is advanced for lapping uponsaidsecond mentioned pole of the magnet being oblique'to the edge ofsaid pole, whereby its lap upon said pole commences at one angle of atriangular area and increases by the movement of said triangular areaonto the pole Whereby the rate of increase of lap ina given movement ofthe shunt, caused by the thermostatic device; is governed by the form ofsaid moving edge.

In testimony whereof-I have hereunto set 25 my hand this 28 day ofSeptember 1914. THEODORE J. FISCHER.

Witnessest' V EDNA M. 'MAoINTosH, LUCY I. STONE.

' Copies of this patent may be obtained for five cents each, byaddressing the Commissioner of .E'atentnv i 7. Washington, 13.0.

